Solar energy has transformed from a niche scientific curiosity into a mainstream electricity source poised to play an integral role powering the planet this century. But humankind‘s journey harnessing the immense potential of photovoltaics (PV) spans nearly two centuries. Let‘s explore solar technology‘s rich and continuing history…
How Solar Panels Work
Before diving into solar‘s origins, a brief primer explains how these wonders convert pure sunlight into usable electric current. Solar cells contain specially treated materials called semiconductors that exhibit unique electrical properties. When solar photons strike these semiconductors, their energy gets absorbed and transfers to electrons. If this energy transfer occurs across specific layers in the material, it generates stable flow of electrons–an electrical current.
Silicon reigns supreme as the dominant material for solar cells today thanks to its amenable electronic properties and abundance. However, ongoing research discovers new viable semiconductor options all the time. No matter the exact components, connecting many solar cells in an array produces cumulative currents that can power anything from small gadgets to entire buildings!
Why Solar‘s History Matters
Understanding solar technology‘s progression over decades reveals valuable context about today‘s booming industry. Tracing this history helps explain how solar has become affordable and efficient enough for mass adoption beyond niche roles. It also sets realistic expectations for future advances that can further improve solar‘s standing compared to alternatives like fossil fuels.
Consider that pioneering solar cells in the 1950s managed less than 6% efficiency–converting only 6% of incoming sunlight into electric energy. After costly production and with such meager output, prospects for widespread use looked dim. Yet relentless manufacturing refinements and material science innovations have since boosted top-tier solar efficiency tenfold to over 40% today. And with costs plummeting 99% in the past half century, solar PV electricity now beats fossil fuel power on price across most world regions.
Intrigued to learn what fueled this tremendous scale-up? Let‘s dive into solar energy‘s complete history…
The Early Days: Discovery of Photovoltaics
Wind back the clock to 1839, when French physicist Alexandre Edmond Becquerel conducted early experiments around the strange behavior of electricity and light. Using an electrolyte cell containing metal electrodes in a conductive solution, Becquerel noted small surges of electrical current when exposed to light.
Varying the experiments using electrodes made of materials like platinum or silver continued generating these photoelectric currents. The fledgling discovery of converting light to electricity became termed the "photovoltaic effect"–with photo referring to light and voltaic pertaining to electricity.
For some 40 years, confusion reigned over what underlying physics powered Becquerel‘s curious PV effect. It took no less than Albert Einstein, who later won a Nobel Prize for explaining the phenomenon. Einstein‘s particles of light concept (photons) interacting with matter (like in metal surfaces) proved vital to unlocking early solar cell avenues.
Inside solar cells, photons with enough energy can strike atoms in semiconductor materials to knock loose electrons. If harvested and channeled before dissipating, these liberated electrons create PV-derived electrical flows.
Early Solar Cell Materials and Innovations
American inventor Charles Fritts built what‘s considered the first true solar cell in 1883. Fritts‘ device consisted of a metal plate coated with the semiconductor mineral selenium and topped with a thin gold film. This formed a primitive solar cell "junction" able to convert sunlight into electrical energy, though at woefully low efficiencies under 1%.
Experimenters soon found that selenium cells proved unstable and otherwise ill-suited to harness sunlight. Alternatives such as copper oxide and eventually silicon offered better conversion efficiencies and stability. Yet lackluster outputs coupled with high expenses stalled meaningful progress for decades.1907
Bell Laboratories researchers Daryl Chapin and Calvin Fuller developed an early silicon solar cell in 1953. The cell‘s layered silicon design with trace boron and gallium dopants created a crucial P-N junction necessary for the PV effect in silicon. Their cell managed about 4% solar conversion efficiency–modest but a watershed moment for silicon PV viability.
| Era | Landmark Solar Cell Efficiency |
|---|---|
| Early Selenium Cells | <1% |
| Bell Labs Silicon Cell (1954) | 4% |
| Hoffman Electronics (Mid 1950s) | 8-10% |
| Space Age Cells (Mid 1960s) | 14% |
Through the 1950s, research groups like famed Bell Labs and Hoffman Electronics (~1957) made steady cell efficiency gains. New fabrication techniques to grow very pure crystals and dope silicon with ions enabled big leaps creating the above milestones.
The Space Age Lifts Solar cell technology
When the Soviet Union launched Sputnik, the world’s first orbiting satellite in 1957, it kicked the Space Age into high gear. The global space race also catalyzed a solar technology boom leveraging funding flows for aerospace innovations. Silicon solar cells experienced particularly quick improvements in efficiency and cost, making them viable to power satellites and spacecraft.
Teams of scientists in government labs and private companies succeeded in enhancing cell performance from about 8-10% availability to 14% by 1965. These gains resulted from improved silicon purification, device engineering, and manufacturing enhancements. More durable and efficient space cells lowered costs through scaling production. New encapsulation and panel assembly methods also evolved to withstand the harsh conditions of space travel relative to ground uses.
Ongoing space industry demands coupled with growing public interest in alternatives energized solar innovation from the 1960-70s onward. Especially following 1970‘s oil shocks and energy cost volatility, solar enjoyed surging R&D monies to hedge oil dependence. Significant efforts made residential solar heating economically accessible during the 1970s as well. Total installed solar electric capacity in the U.S. alone swelled from just 1 megawatt in 1971 to over 80 megawatts per year by the end of the decade.
Accelerating Progress in the 80s and 90s
From early silicon cells to today‘s futuristic ultra efficient designs, no factor proved more crucial than production cost reductions driving adoption. Innovations in manufacturing and cell/panel fabrication unlocked immense savings decade upon decade.
When Bell Labs first developed its silicon cell in 1954, the very process of making semiconductor grade silicon itself exceeded $150 per kg. Through the space program and beyond, the quest for purer silicon and less material waste delivered huge cost declines. Improved chemical growing methods like Siemens and enhanced Czochralski crystal pulling became widespread by the 1980s. These helped slash prices from >$150 to around just $20 per kg over 30 years.
With silicon feedstock far cheaper, new economies of scale making wafers and cells added more gains. Automation replaced slow, costly batch processing and custom assembly relied on by early solar firms. Hundreds of individual cell fabricators and panel producers emerged, especially overseas, benefiting from these automation tools. Silicon wafer prices eroded 90% from $6 per Watt in 1976 to about $0.60 per Watt by 1986. Panel prices saw similar trajectories, as this 1985 Department of Energy outlook table conveys of achieved cost declines:
| Product | 1976 Price | 1986 Price | % Change |
|---|---|---|---|
| Silicon Material per kg | >$150 | ~$20 | -87% |
| Silicon Wafers per Watt | $6.00 | $0.60 | -90% |
| Solar Panels per Watt | $76.67 | $4 | -95% |
Ongoing enhancements in manufacturing efficiency combined with maturing c-Si technology to make solar cost competitive with fossil energy in many regions entering the 2000s. Some experts partially credit solar‘s 10% average cost declines since 1980 to Swanson‘s Law, akin to Moore‘s famous maxim for computer chips. Developed by solar pioneer Richard Swanson, it states costs drop 20% for every doubling of shipped solar photovoltaic capacity.
Beyond incremental panel improvements, the 1990‘s saw explorations of radically new solar cell designs to push efficiency limits. Teams globally tested multi-layer cells with two, three or more interacting semiconductor junctions. Stacked cells split the solar spectrum‘s wavelengths to drive individual sections for better total capture. Later concentration PV techniques used lenses or mirrors to multiply light exposure on tiny super cell arrays.
Though very costly then, such next gen concepts began paying dividends in the 2000s…
The 2000s PV Revolution
Entering the 21st century, cumulative solar electric capacity worldwide totaled a meager 1.5 gigawatts (GW). But with swelling production scale and ever cheaper cells, the floodgates preparing for decades finally opened. The 2000s saw solar adoption skyrocket tenfold in under 10 years. Followed by another tenfold explosion from 2010-2020.
Driving thisRecent exponential growth came powerful new solar cell materials and designs…
1. Thin Film PV
Traditional silicon cells required thick, hyper pure crystals adding to production costs. New thin film technologies needing up to 99% less Si and easier assembly methods gained steam in the early 2000‘s. Manufacturers bonded microscopically thin chemical coatings, just a few microns thick, with glass, metal or plastic sheets outputting usable power.
While less efficient generally than Si options, thin films (using cadmium telluride) offered major per unit savings. First Solar became an early thin film success story, among the largest global solar firms today.
2. Organic PV Films
Research into even cheaper organic PV materials advanced too. Rather than inorganics like silicon, organic cells use carbon-rich polymers and dyes from sources like plastics. Eastman Kodak notably developed early organic solar tech in the late 1970s. Although far from commercial viability then, by the 2010s companies made strong inroads.
Heliatek for one claims over 13% efficiency organic solar–an emerging challenger improving yearly.
3. Concentrator PV
Concentrator PV as noted earlier directs amplified sunlight onto smaller but far more efficient solar cells. Built around advanced multi-layer cell materials, CPV surpasses 40% efficiency in commercial modules today. Though representing under 1% of solar installed currently, CPV promises to raise yields on large solar plants as costs decline.
4. Quantum Dot Solar
Quantum dots (QDs) are nanoscale semiconductor particles with attractive light absorption traits for PV efficiency. These microscopic quantum dot spheres can be tuned to different sizes to capture a wider energy spectrum from the sun. QD solar cells remain in early R&D but show enormous promise says researchers given rapid efficiency increases over the past decade.
The Explosive Growth of Solar Farms
Buoying total solar capacity additions most recently are massive utility-scale solar developments known as solar farms. The favorable economics of ground-mounted solar panels combined with open unused land spurred private investments and public infrastructure spending.
The U.S. currently leads the world with over 40 GW of large-scale solar capacity after more than tripling since 2016. However China and India boast equally ambitious development pipelines expecting to add hundreds of gigawatts more in the next few years. Global solar farm capacity now exceeds an estimated 330 GW as of 2022 based on industry data.
Let‘s survey some record-setting solar plants pushing possibilities:
Topaz Solar Farm – One mega project leading scale advances is the Topaz site spanning 25 square miles of central California. Its 9 million thin film PV modules yield 550 MW total–enough to power 160,000 homes annually.
Bhadla Solar Park – Located in northwestern India, Bhadla ranks among the largest integrated solar parks worldwide. Current and planned solar projects at Bhadla will reach 2245+ MW upon final expansion under Phase III.
Tengger Desert Solar Park – China‘s renewable megaprojects include the mammoth Tengger complex in Gansu province. Planned for a stunning 20,000 MW capacity able to deliver electricity demands of ~5 million Chinese households.
The Future of Solar PV
Industry analysts and scientists alike see immense prospects for solar innovating further in the years ahead. Continuing to reduce costs while improving efficiency and storage capabilities can make solar the globe‘s predominant electricity source within this century.
Current Levelized Cost of Energy (LCOE) metrics already show solar undercutting coal and gas across more world regions annually. Experts forecast another 40-50% drop in average total solar expenses by 2030. That includes cheaper advanced silicon cells hitting 29-32% efficiency alongside newer thin film and multi-layer options.
Likewise battery and renewable hybrid storage to enable overnight solar power will grow economically feasible before mid century. These clean energy systems leveraging solar, batteries and supplemental generation will make reliable 100% renewable electric grids possible at scale.
With such enormous promise, solar energy‘s transformative journey appears just beginning!
